As far as I know there are few ways to resolve an unconfirmed (unstuck) transaction.
1. CPFP (child-pays-for-parent) 2. RBF (replace-by-fee) 2.1 FSS-RBF (first-seen-safe) 2.2 Full-RBF 2.3 Opt-in RBF 3. Requesting Miners to push unconfirmed transaction to their Memory Pool
My question is simple:
Regardless of the wallet type, If USER A does a stuck transaction to USER B. How can USER C (myself) resolve unstuck transaction with minimum input possible from Both the Parties (User A and User B)?
What do I mean by Minimum input is that, if I were to do CPFP, I would need to have Private Key of the User B to do Child Transaction using Coinb.in
But I don't think its possible (neither good) to acquire Private keys of User B even if I know them really well (a friend) because if I know their private key I have complete control of their wallet and I can control his/her future transactions too.
I prefer avoid the use of private key. Any better Alternatives or suggested method User C, User A or User B can do to fix unconfirmed Transactions?
What Miners do
Miners only ask for the transaction ID and they charge X (some) amount to push unstuck transaction to their next block. This is quite good but I prefer doing it without the help of a Miner.
Replace By Fee
Opt-in RBF, is possible only if user opted in for RBF in advance and only if their wallet supports such RBF Method. This is not alwayz the case.
FSS RBF is to replace the current existing low fee transaction using a higher Fee. And to achieve that it requires that the RBF transaction include the same outputs (unspent) as the transaction it replaces and consumes the same inputs (reciever's public address to which the bitcoin is sent).
FULL RBF is quite expensive for cases with big transactions. If the transaction was originally 3 bitcoin then to create new transaction to do FSS RBF with higher fee would require again 3 bitcoin which is quite expensive.